Soaking pits



O. M. BLOOM SOAKING FITS June 17, 1958 6 Sheets-Sheet 1 Filed Jan. 6,1954 INVENTO R QUENTIN M. BLOOM XNI ATTORNEY 6 Sheets-Sheet 3 Q. M.BLOOM SOAKING PITS June 17, 1958 Filed Jan 6, 1954 INVENTOR QUENTIN M.BLOOM ATTORNEY Q. M. BLOOM June 17, 1958 SOAKING FITS 6 Sheets-Sheet 4Filed Jan. 6, 1954 INVENTOR uarrrm M. BLOOM ATTORNEY June 17, 1958 Q. M.BLOOM 2,839,290

' SOAKING PITS Filed Jan, 6, 1954 6 Sheets-Sheet 5 m m 11 m m m to k (um a 2 0 3 I ,1

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ATTORNEY k 6 Sheets-Sheet 6 INVEN TOR QUENTml M, BLOOM BYX fi ATTORNEYO. M. BLOOM SOAKING PITS June 17, 1958 Filed Jan. 6, 1954 Unite assgzaeSOAKING rrrs Application January 6, 1954, Serial No. 462,492

6 Claims. (Cl. 266-) The present invention relates to the constructionof furnaces of the type commonly referred to as soaking pits which arein common use in steel mills for the purpose of heating ingots to adesirably uniform steel rolling temperature which varies with operatingconditions. Soaking pits now in use in this country are customarily deepchambers, or underground furnaces of square or rectangular sections withtop openings normally closed by removable covers. A typical modernsoaking pit for heating blooming mill ingots is large enough to holdfrom eight to sixteen ingots each in an upright position. Each suchingot may be about six feet tall and is substantially square orrectangular in cross section, with one side about twenty-three incheslong at its lower end. Each ingot is customarily tapered, being somewhatsmaller at its upper end than at its lower end. Usually each ingotinserted in a steel mill soaking pit, is a hot steel casting, the innerportion of which may still be molten when the ingot is inserted in asoaking pit. Cold ingots are ordinarily put into soaking pits only instarting a rolling mill into operation following a shut down so that nohot ingots are then available. in normal operation, a hot ingot insertedin a soaking pit needs to be subjected to a suitable and suitablyuniform temperature for several hours. The soaking period issubstantially longer .for ingots which are cold when put into thesoaking pit. The heating of ingots in soaking pits has long beengenerally recognized as highly ineflicient, although the heatingprovisions usually include regenerators or recuperators external to thesoaking pits.

A general object of the present invention is to provide a soaking pitwhich is more efficient than the soaking pits heretofore in use, and ischaracterized by the transfer of heat to the opposite sides of eachingot being soaked, by radiation from the adjacent side walls of thesoaking pit. To this end, the side walls of the soaking pits areadvantageously provided with burners comprising open ended combustionchambers in the form of circular cavities in the side Walls of the pitsand comprising a separate burner pipe or conduit coaxial with andextending into each cavity from the outerportion of the furnace wall,and discharging a combustible mixture of fluid fuel and air which burnsalongside the cavity wall in the general manner disclosed in the FurczykPatent 2,561,793 of July 24, 1951.

A further and practically important object of the present invention isto make effective use of individual soaking pits each having relativelysmall ingot holding capacity. instead of using a soaking pit largeenough to simultaneously hold eight or more ingots distributed indifferent horizontal directions, I ordinarily use a soaking ,pit onlylarge enough to hold a single short horizontal row of ingots. Inpractice there may well be three ingots in each row, with the ingots ineach row receiving radiant heat directly from the uprising heating wallsadjacent the elongated sides of the rows.

Such reduction in the size of the soaking pits employed Zfififi PatentedJune 17, 1958 radiant heating walls, contributes to increased efiiciencyby reducing the soaking pit cooling action which is an inevitable resultof the heat loss occurring when the upper end of the soaking pit isperiodically opened, as is necessary, for the removal of ingots readyfor rolling, and for their replacement by ingots to be heated. The rateat which heated ingots are withdrawn from each soaking pit, ordinarilydepends upon the operating characteristics of the associated rollingmill. If, as may well be the case, three ingots are advantageouslywithdrawn at one time, each ingot after being inserted in a soaking pitis necessarily subjected only to a single cooling and scaling actionprior to its passage to the rolling mill. .If ingots are withdrawn threeat a time from a soaking pit holding twelve ingots, for example, on theaverage, each ingot willnecessarily be exposed to at least four separatecooling and scaling actions prior to its passage to the rolling mill.

In the use of the presentinvention, a separate cover structure isprovided for each soaking pit with the re sult that the weight of eachindividual cover is much smaller than the weight of the cover for thelarger soaking pits heretofore used. The reduction in the weight of acover means a reduction in the amount of power required for the removaland replacement of the cover, and some reduction, also, in the timerequired to remove and replace a cover. In practice, a plurality ofcovers may be moved out of and back into their normal positions along asingle pair of track rails.

The replacement of a single large soaking pit by a plurality of smallersoaking pits makes it practically feasible to effect closer control ofthe heating operation of. the individual soaking pits with the practicaladvantage in some cases of reducing the time required for heating theindividual ingots, and with the desirable result that the average timerequired for heating an ingot is reduced and in consequence a reductionin the number of ingots necessarily being heated at any one time tosupply the heated ingots required in a mill plant of given size.

A further object of the invention is to provide soaking pits with floorswhich can be readily removed for repair or replacement without work onor contact with other portions of the pits. The ability to remove andreplace the floor of a soaking pit Without disturbing the rest of thesoaking pit structure is practically important, since in normaloperation the floor of a soaking pit is subjected to more need forrepairs and reconstruction than all of the remaining portions of the pitstructure.

A further and important object of the invention is to provide a soakingpit structure in which the roof or cover closing the upper end of asoaking pit or pits is suspended from overhead supporting means at alltimes. Such suspension avoids the warping or flexing of the cover, andresultant cracking of the cover refractories, heretofore experiencedwhen the pit cover is normally supported on the vertical pit walls, butis suspended from an overhead structure when the cover is moved to openup the soaking pit for the removal and insertion of ingots.

The various features of novelty which characterize my invention'ar'epointed out with particularity in the claims annexed to and formingapart of this specification. ever, its advantages, and specific objectsattained with its used, reference should be had tothe accompanyingdrawings and descriptive matter in which I have illustrated anddescribed preferred embodiments of the invention. Ofthe drawingsz. V 1

Fig. 1 is a diagrammatic plan viewof an ingot heating and preheatingstructure;

Fig. '2 is a partial section on the line 22 of. Fig. 1; Fig. 3 isalpartial section on the line '33 of Fig. 1; Figs. 4 and 5 are sectionstaken'on' a portion of the line 2F-2, and on the line 33 of Fig.1,respectively, showing soaking pit floor portions on larger scale and in.

greater detail than they .are shown in Figs. 2 and 3,

respectively; I

Fig.6 is a diagrammatic plan view of asoaking pit furnace cover; p I 1Fig. 7 is an elevation in section on' the broken line 77 of Fig. 6;

Fig. 8 is a section on the line 8-8 of Fig. 7;.

Fig. 9 is a diagrammatic elevation of means for sup plying fluid fueland combustion air to the burners of an individual soaking pit; and

Fig. 10 is an end elevation partly in section through a soaking pit, andillustrating bottom wall hoisting apparatus.

The soaking pit structure .1 shown diagrammatically in Fig. l,compriscs'four main soaking pit chambers 2,

3, 4 and 5, and two preheating pit chambers 6 and 7. In theparticular'constructionshown, three vertical ingots 8 are arranged'sideby-side in a straight row in each of the pits 2,. 3, 4, 5, 6 and 7. Thepit 3 is arranged in end-to-end relation with the pit 2, and the pits 4and 5 are arranged in end-to-end'relation with one another, and arerespectively alongside the pits 2 and 3, but are spaced away from'thelatter. Each of the pits has vertical refractory walls 9 at its sidesand ends and each side wall of each of the pits 2, 3, 4' and 5 is formedwith a plurality of burners 10. Eachburner locomprises a wall cavityopen to the pitch amber and a separate pipe 11 which opens into thecavity, and normally discharges a mixture of air and fluid fuel therein.Ordinarily, the fuel will. be gas, and it is noted by wayof illustrationand example that the burners may be constructed and arranged in thegeneral manner shown in the Sisto and Milos application, Serial -No.362,293, filed June 17, 1953. The manner in which air and fuel issupplied to the burners 10'ofeach of thepits 2-5, is illustrateddiagrammatically in Fig. 7 9, and 115' hereinafter described. Thepreheating pits. 6 and. 7 are generally similar in shape to, and arealongside the ingot heater pits 4 and 5.

Channels 12 formed in the masonry walls alongside the soaking andpreheating pits, and including portions below the level of the botomwalls-of the chambers 2 to 7, pass the gaseous products of combustionformed in the pit chambers 2, 3,4 and 5, intothe preheating pit chambers6 and 7 and thence to the chimney 13, as indicated by the arrows 14shown in Fig. l. i

The lower end of each of the pits 2 to 7 is normally closed by aremovable'bottom wall or floor 15. In accordance with the presentinvention, each pit floor is readily replaceable; 'As shown in Figs. 4and 5, the floor of the pit z comprises refractory material 16 directlysupported by metal plates 17 and a metallic rimfram'e 18. The plates 17'and frame 18 are attached to and supported by metallic channelbars orbeams 19 which normally rest on the beams 19a of a metallicsub-structure. The rim frame 18 is shown-as of angle bar cross sectionwith its horizontal flanges extending inward from anouter vertical baseflange, ,ZThe Ffloor member is slightly shorter and narrower than thesoaking'pitzin which it is mounted. Each side and end of the frame 18 isspaced away from an adjacent. vertical wall of the cor- For a betterunderstanding of the invention, howresponding pit, and, as shown, isdirectly supported by a 'subjacent channel bar or beam20l 'Each'such'beam 20 is alongside a beam or channel bar 20a beneath the adja cent pitWall.

The space between theadjacent beams or bars 20 and 20a is closed byhorizontally elongated bricks 21. Each beam 20 and the adjacent beam 20aare provided with brackets 22 and 23. The side-by-side brackets 22 and23 support the bricks 21, or analogous refractory members. Those memberssupport a mass of refractory filling material 24, which normallyconsists mainly of slag and scale, and which extends upward to a leveladjacent the top of refractory floor material 16. When it becomesnecessary to open or replace a floor member 15, the associated bricks 21are broken and the slag, scale and other material above the bricks arepermitted to -flow down into the space below the beams 19a; The abilityto readily make the pit floors accessible for replacement or repairs isof substantial practical importance, par-. ticularly as the floors offurnace pits are customarily rebuilt at relatively frequent intervalsprimarily. because of undesirable changes in the composition of thefloors due largely to' scale deposits. After the bricks 21 associatedwith the bottom wall 15 have been broken away, the bottomjwall may belifted verticallyout of the corresponding soaking pit for repairs orreplacement.

As is diagrammatically illustrated in Fig. l0,the bottom wall in thesoaking pit 2 is shown in engagement with hoisting apparatus.Thatxapparatus includes a cable depending from an overhead crane oranalogous hoisting element, andtong elements 71 having their upper endssecured to the lower end of the cable 70 and each having a lower portionpassing downward 1 between adjacent channel bars 20 and 20a, and havingitsho'ok end 73 extending beneath and engaging the underside of thebottom member 15. The isoaking pit 2a shown in Fig. 10 may be identicalin structure to the pitsfshown in Figs'. l, 2, 3, 4 and 5, but some ofthe structural details shown in the last mentioned figures are omittedin Fig 10.

As shown in Figsi4 andS, each ingot 8 in a pit cham ber may well besupported on four tubular'water cooled pins 25 which extend verticallythrough the floor struc- 1 ture and to a'level a few inches above thetop ofthe refractory body portion 16 of the floor. H Each pin 25 Theupper end of'each of the soaking and preheating pits is provided with aseparate readily removablecover 30. In accordance with the presentinvention, each cover comprises an upper crane-like supporting structure31.

having a platform-like body with spaced apart wheels 32 and 33,respectively adjacent each of two opposed edges of the structure 31. Asshown, the two wheels 32 "are driving wheels connected by an axle 34 andthe two wheels 33 are idler wheels connected to a separate axle 35mounted in the structure" 31; The driving wheel axle 34 is connected byspeed reducing gearing to a'driving motor 36 mounted on the stru cture31. The motor'36 mounted oneach member 31 is arranged to move thelatter, along track rails 37 supported by thesoaking pit structure 1between its soaking pit closing position, and

a position at one side of said closing position.

As shown in Fig. l, the cover supporting members 31 associated with thesoaking'pits 2, 4 and 6 are movable along the. same pair of track rails37 transverse to the length of the opposite ends of each of said pits2,4 and 6, and each platform structure 31 and the cover suscalled aparking position. As shown, there is sparking space 38 at the right ofeach of the pits 2, 3, 4, .5 and 6. The covers for the pits 3 and .5 runon a second pair of rails 37 parallel to the first mentioned rails 37. Aparking position 38' is provided for the cover 30 which normally closesthe upper end of the pit 7. The last mentioned cover has its wheels 32and 33 arranged to run on track rails 37.at right angles to the rails37. The contemplated spacial requirements of the structure 1 shown inFig. 1 make it desirable to have the rails 37' at right angles to therails 37. As will be apparent, whether one or more pairs of track railsare transverse to the long or short side of the associated pit maydepend on conditions.

Each cover member 30 is suspended from the corresponding supportingmember 31 for up and down movement between a lower position in which thecover 3% extends into and closes the upper end of the correspondingsoaking pit, and an upper position in which the cover 30 is above thetop wall of 'the soaking pit structure and will not interfere with themovement of the member 31 horizontally along the corresponding trackrails 37 or 37'. As shown, each cover member 34 is suspended from thecorresponding supporting member 31 by bell crank levers 39. As shown,there are four levers 39, each pivotally connected intermediate its endsto the structure 31 by a corresponding pivot 39a. The lower end of eachlever 39 is connected tothe cover 30 by a link 3%. The latter has itsupper end pivotally connected to the lever and having its lower endconnected to the cover 30 by a removable pin 3%.

The upper end of each lever 39 is connected by a pivot 39c to a separatelink 4% The links 40 connected to the two levers 39 adjacent the leftend of the member 31, have their second ends connected to aligned crankpins 42 rigidly connected to and laterally displaced toward the left endof the member 31 as seen in Figs. 6 and 7 from a crank shaft 41 parallelto the track rails 37. The links 4-0 connected to the two levers 39adjacent the right hand end of the member 31, as seen in Figs. 6 and 7,are connected to crank pins 422 rigidly connected to the crank shaft 41angularly displaced 180 from the crank pins 42. The crank shaft 41 isarranged for rotation through speed reducing gearing by a second motor43 mounted on the member 31.

As shown, each cover is provided with 21 depending flange 44 along thesides and ends of the structure and normally extends into a sand seal55, thus providing an effective seal against air or gas leakage into orout of the corresponding soaking pit. Each cover member 3i includes amass of bricks or other refractory material of poor heat conductivitysuspended from metallic framework beam port'cns d6 of the cover member36. Since the weight of the cover 3% is supported at all times by thestructure 31, the movement of the cover into and away from its normalclosed position does not tend to flex or strain the cover structure, asit would if the cover were supported in its closed position by the wallsof the corresponding pit and were suspended from the member 3i whenmoved upward away from its normal position.

In accordance with the present invention, provisions are advantageouslymade for a separately regulated supply of fuel fiuid and combustion airto each of the main heating pits 2, 3, 4 and 5, so that the rate atwhich heat is supplied to each of those pits may be independentlyadjusted. Such regulation is especially desirable during operatingperiods in which the rates at which ingots are supplied to and withdrawnfrom the pits 2, 3, 4 and fluctuate. Ordinarily, when the normaloperation is thus upset, the rate at which the combustible fuel mixtureis supplied to the burners in one main soaking pit should be variedrelative to the rate at which the mixture is supplied to the burners inone or more other main soaking pits. in the particular constructionillustrated, each of the two side Walls of each of the pits 2, 3, d and5 has sixv burners 10 directly facing the adjacent side of each ingot inthe pit, and the six burners are-located at four difierent levels, oneburner at each of two upper levels and two burners at each of two lowerlevels. The fuel and air mixture supplied to each burner may be mixed ateach burner, as is done in the apparatus disclosed in said FurczykPatent 2,561,793.

As is shown diagrammatically in Fig. 9, the fuel and combustion air maybe separately passed to the burners 10 of each of the soaking pits 2, 3,4 and 5 through piping of the character diagrammatically illustrated inFig. 9. in that figure, fuel gas is supplied under pressure to the inletside of a throttling valve 50 located at a level above the soaking pits8. The valve 50 passes gas at a regulated rate into the upper end of apipe 51 which extends down through the soaking pit structure into atunnel 52 below the channel 12, and then passes into an uprising gaspipe 53. The latter is connected to a horizontal manifold 54 which hasfour vertical branches 55, 56, 57 and 58 at the outer side of one sidewall of the pit 2. Those four branch pipes are distributedlongitudinally of the pit 2 and of the three ingots 8 therein so thatthe branch 55 may supply gas to four burner pipes it associated with theingot 3 adjacent the left end of the pit 2. As shown, two of those fourburner pipes 11 are located at difierent upper levels and the other twoburners are located at different lower levels. The branch 56 suppliesfuel gas to two burner pipes 11 at different lower levels and alongsidethe lower portions of each of the two adjacent ingots, and supplies fuelgas to one upper burner pipe 11 associated with the central ingot in thepit 2. The branch pipe 57 supplies fuel gas to burner pipes 11 atdifferent lower levels associated with each of the two ingots adjacentthe right ended the chamber 2, and supplies fuel gas to one of the twoupper level burner pipes alongside the central ingot. The pipe 53supplies gas to four. burner pipes 11 at different levels alongside theingot 8 adjacent the right end of the pit 2.

An air compressor 68 above the soaking pits and draw ing air from theatmosphere, supplies air under suitable pressure to the upper end of apipe 61 which is substantially larger in cross section than the pipe 51.The pipe 61 extends down into the tunnel 52 where it is connected to anuprising pipe 53 supplying air to a manifold 64 alongside the manifold54 and provided with four branch pipes 65, 66, 67 and 68. Each of themanifold branch pipes 65, 66, 6'7 and 68 may be arranged to supplycombustion air to the burner pipes 11 which receive fuel gas from thecorresponding fuel gas branch pipes 55, 56, 5? and 58, respectively. Thevalve 50 and blower associated with the soaking pit 2., mayadvantageously supply gas and air, respectively, to manifolds and branchpipes and burner pipes 11 in the side wall of the pit 2 which is injuxta-position to the side wall shown in Fig. 9. Y

The mixture of fluid fuel and air passed to the burners isadvantageously proportioned so that all of the gas is burned and so thatthe amount of excess air is relatively small in amount. With the fueland air so proportioned, it is not difficult to regulate the fuel andair supply as required to vary the combustion rate and thereby thetemperature in the pits 2, 3, 4 and 5, while at the same time heatingthe dished refractory ourner wall surfaces to incandescence, and thusmaintain a relatively high ratio of the radiant heating effect to theconvection heating effect.

As has been made apparent, the invention is characterized in particularby the relative ease with which each bottom wall 15 may be removed forrepair or replacement. The vertical extent of the piers 19b issuflicient to permit a workman to move around in the space beneath thebeams 19a. Thus the bricks 21 may be readily broken and removed, andsubsequently replaced after the repaired or replacement bottom wall isput in place on the beams Furthermore, each bottom wall may be soakingpit is out'of regular operation.

The means for the continuous suspension of the soaking pit cover member30 in normal operation, not only avoids -"the risk of objectionabledistortion of the cover member but-facilitates the separation from thesupporting structure 31 of a damaged cover member and the subsequent 31may be attached to the latter by the replacement of the pins 3%.

While in accordance with the provisions of statutes,

I have illustrated and described the best form of embodiment of myinvention now known to me, it will be apparent to those skilled in theart that changes may be made in the forms of the apparatus disclosedWithout departing from the spirit of my invention as set forth in theappended claims and that in some cases certain features of my inventionmay be used to advantage without. a corresponding use of other features.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. A soaking pit structure comprising a plurality of side by sidesoaking pits each proportioned .to receive a single short row of spacedapart vertical ingots with each pit having a refractory side wall closeto each side of said row and an end wall close to each end of said row,each of said side walls being provided with a plurality of fluid fuelburners directed toward each of the ingots between them and spaced overan area of said Walls substantially equal to the area of the ingots andthe configuration'of the ingots and operative to pass a large portion ofthe heat generated by the burners in the form'of radiant heat withoutflame impingement to the sides of ingots between and facing said sidewalls.

2 A soaking pit structure comprising a plurality of side by side soakingpits each proportioned to receive a single short row of spaced apartvertical ingots with each pit'having a refractorysidewall close to eachside of said row and an end wall close to each end of said row, aplurality of fluid fuel burners in the portions of each of said sidewalls immediately adjacent the sides of each of said'ingots and spacedover an area of said walls substantially, equal to the area of theingots and the con: figuration of .the ingots .and directed toward them,said burnersbeing operative to pass a large portion of the heatgeneratedto the ingots in the form of radiant heat and without flame impingement,a removable cover normally-closing the upper end of each pit and meansfor passing gaseous products of combustion away from the soaking pit.

3. A- soaking pit structure comprising vertical walls surrounding asoaking pit chamber, a removable cover normally closing the upper endofsaid chamber, means for passing heating gases into and out of saidchamber,

1 fi t pqfi r ml m b h n s pp i walls, a second supporting structurebeneath said chamher and having itsouter'edge displaced inwardly fromsaid'w'alls, a destructible third bottom wall supporting structurebridging the gap betweensaid ifiISt and said second supportingstructures, and refractory material supported by said secondand thirdsupporting structures and forming th'e pit bottom walL-whereby s aid'second supporting structure may be moved upward through said pit chamberwhen said cover is removed'and said destructible supporting structure isbroken. I i

4. A soaking pit structure comprising vertical valls surrounding asoaking pit chambena removable cover normally closing'the'upper end' ofsaid chambergmeans for passing heating gases into andout of saidchamber, a first supporting structure beneath and supporting said walls,a second supporting structure directly beneath said chamber. and havingits: outer edge displaced inwardly from said walls, bricks forming adestructible bridge forming a third bottom wall supporting structureextending between said first and second supporting structures, andrefractory'material supported by said bridge and second supportingstructure and forming the pit bottom wall, whereby said bottom Wall maybe removed through said chamber for repair. or reconstruction uponbreaking said destructible bridge. 1

5. A soaking pit structure as specified in claim 4, in

' which said first and second supporting structures comprise metallicparts forming abutments supporting the opposite ends of the bricksforming said bridge.

6. In a furnace, the combination of a supporting frame, verticallyextending furnace walls outlining it furnace chamber on said frame, afurnace floor slightly smaller in area than said chamber resting on saidframe within the confines of said walls, shelf means on said walls andextending inwardly from said walls toward said floor, additional shelfmeans on said floor and extending outwardly toward said walls, aplurality of re' movable bricks resting on said shelf means to bridgethe gap between said walls-and floor, removable refractory material onsaid bricks to seal the space between said floor and walls, a removableroof for saidchamber, and means to support saidroof above said walls ingas tight relation therewith.

References Cited in the file of this patent I UNITED STATES PATENTSOTHER REFERENCES Page 9 of Trinks Industrial Furnaces, vol. 1, 3rd ed,copyright 1934; John Wiley and Sons, New York, N. Y.

